McMahon will pen the hour about a family that moves into an idyllic community where medicine and technology are the closest thing to Utopia -- until they suspect that something darker might be afoot.

Peter Traugott and Rachel Kaplan will executive produce Maddox, which hails from Universal Television and TBD Productions; ER's Lisa Zwerling will serve as a supervising producer.

McMahon served as a production staffer on Shonda Rhimes' Grey's Anatomy in 2009 and segued to a researching gig with the prolific showrunner's spinoff, Private Practice from 2009-11, penning an episode of the Kate Walsh starrer last yea and contributing to the medical drama's blog.

The sale marks Traugott and Kaplan's latest project this development season. The duo has an untitled Southern Gothic drama and Donald Glover's semi-autobiographical comedy all set up at NBC, among others.